Oscillation-detecting means for receiving intelligence communicated by electric waves.



G. W. PIOKARD. OSGILLATION DETEGTING MEANS FOR RECEIVING INTELLIGENCE OOMMUNIGATED BY ELECTRIC WAVES. APPLICATION FILED MAR. 11, 1907.

Inventor;

Patented Nov. 1-7, 1908.

UNITED STATES PATENT. OFFICE.

GREENLEAF WHITTIER PIOKARD, JOF AMESBURY, MASSACHUSETTS.

OSQILLATION-DETECTING MEANS FOR RECEIVING-INTELLIGENCE COMMUNICATED BY ELECTRIC WAVES.

Specification of Letters Patent.

Patented Nov. 17, 1908.

Application filed March 11, 1907. Serial No. 361,659.

Receiving Intelligence Communicated by Electric lVaves, the principles of which are set forth in the following specification and accompanying drawing, which disclose the form of the invention which I now consider to be the best of the various forms in which said principles may be embodied.

This invention relates to oscillation detecting means for receiving intelligence communicated by electric waves, as by wireless .telegraphy or telephony.

The object of the invention is to obtain a detector of the thermo-electric regenerative class disclosed in my Patent No. 836,531 of Xovember 20, 1906, with all the accompanying advantages, which shall in addition have permanent operativeness'in being capable of absolutely permanent operating adjustment. Detectors of this class cbmprise two massive electrical conductors cooperatively having high thermo-electric power, and in contact, but mechanically distinct, to establish a high resistance thermo-junction, the electrical contact being good at the high resistance junction, and the massive conductors having low resistance circuit contacts. These conductors are massive, in the sense that their structural dimensions are not such as will offer a sufiicient. resistance to thc oscillating currents, to materially dissipate their energy in the form of heat in the mass of the conductors themselves, before the currents can effectively reach the high resistance junction. Such massive conductors are thereby (2'. 6., by not having essential structural limitations) distinguished from conductors which are artificially attenuated to.

produce high ohmic resistance, and from those conductors which naturally have the attenuated form, as of a crystal, accompanied by high ohmic resistance due to structure and not.- to specific resistance. The differentiated conductors of high structural ohmic resistance are not suitable for use in this invention, because that resistance causes a dissipation of the oscillating current energy in the mass of the conductors themselves, thus not permitting sufficient energy to reach and heat a thermo-junction to a practically operative degree.

The invention consists of the novel subject matter hereinafter described with reference to the accompanying drawing. and specified in the appended claims.

The drawing is a vertical section of the best embodiment of the invention which I have yet produced.

The invention will be described with particular reference to one particular combination of conductor-materials which I have found to give the best results.

In the drawing the massive men'i'bers are shown at Y and P, in contact at T J to c.- tablish the thermo-junction of high resistance. The massive member Y is composed of the sulfid molybdenite, which is the mineral-ore and chemical compound with sulfur of the metal molybdenum. This compound is of no value as an element of a detector unless itis employed in accordance with this invention. Butv it possesses properties peculiarly adapted for use in a detector of the massive thermo-electric regencrator class, when so employed. These properties are not possessed by either of its t'UllSillllOlliS, the metal molybdenum, and the element sulfur, the former of which is an excellent. conductor of electricity resembling iron, while the latter is one of the best non-conductors of electricity and could therefore not be used as an element of a thcr1noclcclric regenera-torf Sulfur in nowisc resembles molybdcnite, of which it forms the major part. The compound molybdenite is a soft or yielding and flexible non-metallic substance. normally an imperfect conductor of electricity, and is markcdly graphitic. in appearance and in its ability to makc marks on paper, and is therefore sometimes mistaken.

for graphite. In addition to its high spccific. resistance as a non-niclallic substance. it has a different kind of resistance. which dealt with in this invention.

This compound molyhdcnilc.togcihcr with another suitable massive conductor. cooperatively having high lhcrn1oelcctric power. and in surface contact. with each other to establi h a high resistance junction. and with means for prcssing the two together i= merely establish a good contact at the junction, thesc hcing all the usual rcqnircim-nlof detectors of this general class, will not constitute an operative detector. I have dlscovercd the reason for this, and have proruled a remedy, which not only produces a detector which is operative, but one which is substantially as sensitive as the silicon detector of my Patent No. 836,531 of November 20, 1900.

The essential for detectors of this general class is a high resistance, good-contact, tlwrmo-junclion between massive, mechanicall ,'-distinct couple men'ibers cooperatively having high thermo-electric power. Theoretically, therefore, molybdenite should be an etlicient mas ive member, but I found that practically it was not, when subjected to the ordinary conditions applicable to detectors of the general class. The means by which the compound is made not only a useful element of an o jierative detector, but an essential pan of a most sensitive device, are shown in the drawing. Here the molybdenite. member Y, covered by a piece of copper foil t, rests on the flat surface of a hard rubber support or sleeve R, and engages the upper end of ihc' ieldingly mounted conducting pin 1. which is the other massivemember and extends through the perforation of the part It. to establish a high resistance thernm-junction with the member Y. The copper foil (7 may have soldered to it a lead 1 to one side of the circuit; which may be any suitable one. such as that of my said Patent No. 8 56,33 A second part of hard rubber (Q rests on top of the copper foil C. All the parts 11, C, Y, Q and B are held in a U-shapcd clamping frame F. A screw extends: through thisclamp F and bears on the brass plate B. A spring S forces up the massive member I to make a good contact at the high resistance junction T J, the pressure averaging about two ounces.

In trying to work with molybdenite,-I was unable, in the lack of the above described structure, to obtain results. he pressure obtained at the junction as'by employing a spring against one massive memberfwhich was sufficient to produce good results with other substances. I found to be ineffectual with inolybdenitc; notwithstanding that the pressure was sufficient to obtain a very good electrical contact at the junction, owing to the softness of the compound. It. appeared at first indeed, as if this very character of softness, which caused a large area of junction surface with even a slight pressure, permitted a junction of too low resistance to i provide an eflicient detector. But I observed that the true reason for this peculiar state of affairs was not because the compound had insufficient resistance to be useful in contributing toward the production of a high resistance junction, and not because the junction area was too large or of too low resistance; but because the compound itself en Y massc had a resistance which was not too low, but which was on the contrary too high. I then discovered that the normal excessively high resistance of the mass Y was appart ently due to its laminar structure, the t laminae being not in good electrical contact with each otherythe normal excessive re sistance of the mass in series with the thermo-junction preventing any effective action, either by preventing the oscillating currents from acting on the thermo-juuction so as to be converted into heat, or by preventing the effective flow of any direct current generated by a possible production of heat, or by wasting the energy by the generation of heat in the mass. The mechanical structure above described constitutes means for obviating this defect, because when the screw A is setvcry tightly down on the plate B, so as to subject the molybdenite to a comparatively great pressure,sometimes as great as ten pounds, the condition of the device is altered from inopcrativencss to a state of perfect operativeness and extraordinary sensitiveness. When the molybdcnite is put under this comparatively great pressure, apparently the laminae are jammed into good electrical contact with each oth r. thus reducing the normally excessive resistance of the device to such an extent as to permit the passage of suflicient electrical energy through the eficctive thermo-junction T J to generate sufficient heat to produce and permit sufficient direct current flow to operate the telephone.

The clamping frame F furnishes a suit able means of. applying the high pressure required, which generally could not be con veniently accomplished in a compact structure by means of a spring. The sleeve R is of insulating material because it is in contact with the member Y, and subjected to the high pressure engagement therewith at all times. lVith different samples of molybdenite, the optimum pressure apparently does not vary, being usually about ten pounds. The other member of the device, the pin P, may be of aluminum, the oxid film of which contributes to the high resist-- ance of the junction T J. But I have found that a pin tipped with bismuth, as by solder ing, as shown at. M, ives better and more dependable results with molybdenite, in that this combination apparently possesses higher thermo-electric power. hen Y is of molybdenitc, the conductor P may, however, be of any metal, almost any metal sulfid or conducting chemical compound, any nonmetal or any metalloid; and likewise when Y is an equivalent of molybdenite.

The metallic spring S. which presses the gpin P comparatively gently (one or two f ounces) against the member Y, is held in place by the screw T, which is adjustable by tthe constructor to secure the permanent optiinuni'pressure. After the constructor has adjusted the clamp and spring to the optimum pressure for a given combination, the entire device should be sealed .in a small box with suitable circuit terminals, in order that the user may not alter that optimum adjustment. \Vlien the pin 1 is held by only slight pressure against the conductor Y,'.such that it does not sink to some extent into the latter, sufficiently to hold it rigidly in place, it is better to closely confine the pin in the perforation in the insulator R; in order to prevent relative angular or lateral movements of the conductors which might vary the optimum pressure at the junction, a binding post I) may be provided in the frame F for the other circuit lead A peculiar feature of the member Y, is its adaptability for use in this combination. notwithstanding its soft or yielding nature. The member I. vlicn iii the form of a pin, and forced by the pressure of Spring S against the member Y which is under the clanipinipression, will have its rounded end slightly sunk into the mass 1', without cutting or shearing the mass, so as to greatly increase the apparent junction-area, without decreasing, but on the contrary, increasing, the useful operative effect. The mo'lybdenite is so soft that it yields, even when subjected to such comparatively slight junction-pressure as will not make it operative in this iiivention. This fact might seem to indicate that its inoperativeness under slight pressure, producing apparently large dontact area, was due'to too great contact area, and consequent as low junction-resistance. But this is not true, as above explained; Inasmuch as the operativness is comparatively independent of apparent contact-junction area, the member P need not be in the form of a pin having a sharp or needle point,

but may have a considerable surface in -contact with Y, such as would be constituted by a rounded end of member P as shown in the drawing. Other materials, which do not possess this property of softness, cannot be subjected 'to suflicient pressure to thereby alone have a stable mechanical adjustment,

without iausing such reduction of the junction resistance as to impair operativeness.

It is necessary, not only that the effective thernio-junction T J be a good contact of high resistance, but that the connection of the massiveanembers to the circuit be good contacts having relatively low resistance in order that the useful action will be confined to the junction T J. The structure herein disclosed produces these results, in that the clamp and spring not only respectively produce a suitable high resistance and good contact at T J, but insure a good low. resistance large-arcad contact between Y and C and a low-resistance contact between P and S, these being the means by which, the massivc-ineiiibers are connected in circuit. The contactbetween P'and S, two low resistance conductors, need not be of large area, but it is 'sutlicient if it be of low resistance relative to T J. The contact between Y and C should not only be of low resistance, but of large area, in order that any possible generation of Jouleaii heat at-this contact between the metal C and the high resistance material Y, shall be distributed through so relatively large a mass of material that the resulting temperature rise will be negligible relative to that at T J. In any case, the physical shapes of the conducting massive-ineiiibers are not. material to the invention, except iiisofar as concerns the production of the proper junction T J.

The detector of this invention is nearly as sensitive as the most. sensitive detector liere tofore known, and permits much sharper tuning, owing to the fact that this device is a pure ohmic resistance, practically devoid 'of asymmetric capacity which would interfere with tuning in the oscillation circuit. It is also the most stable detector 1 have ever used. It has withstood the most severe static discharges without the slightest resulting effect upon its sensitii 'eiiess, these discharges being frequently applied at an intensity twenty thousand times as great as that of the received signals. 'Thedevice should not. however be left'ili any wiseconnected with sending circuits, as the heat generated-by the powerful currents therefrom, might be sutficieiit to weld togel her the separate massivemembers and thus break down the high resistance of the contact-junction.

[elaimz 1. 'Oscillation-detecting means for receiviiig intelligence communicated by electric wavesawhich comprises two massive and mechanically distinct electrical conductors cooperatively having high thermo-electric power and in good electrical contact with each'otlier, one of said conductors being nonmetallic and having high specitic resistance; oneof said conductors possessing an excessive resistance in series with thejunction: and means for reducing said excessive resistance to permit effective action by the received oscillations resulting trdin the transmission of the intelligence by electric waves.

2. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high thelrino-electric power and in contact with each other, said conductors being mechanically distinct, and one being non-metallic and having high specific resistance, to establish a high resistance junction: one of said conductorspossessing an excessive resistance in series with the junction: means for reducing said excessive resistance to permit effective action .by the received oscillations resulting from the transmission of intelligence by electric waves; and means for,

pressing the conductors together to establish a good contact at the junction.

3. Oscillationdetecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high thermoelectric power and in contact with each other, said conductors being mechanically distinct, and one being non-metallic and having high specific resistance, to estab lish a high resistance junction; one of said .conductors being a soft yielding chemical compound, and the other being relatively harder; and means for pressing said conductors together to cause the harder conductor to sink into the softer conductor and establish an electrically good and mechanically stable contact at the high resistance junction. 1

4. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high thermo-electric power, and in good contact with each other, said conductors being mechanically distinct, and one being non-metallie and having high specific resistance, to establish a high resistance junction; one of said conductors being a chemical compound having excessively high structuralresistance which is reducible by the application of pressure; and means for compressing said compound to eliminate-its excessive resistance and produce effective high resistance.

5. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high thermo-electric power, and .in contact with each other, said conductors being mechanically distinct, and one of said conductors having high specific resistance, to establish a high resistance junction; one of said conductors having a laminar structure in which the laminae are in. imperfect electrical contact; and means for pressing said laminze into good contact with each other.

6. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high .thermo-electric power and in good electrical contact with each other, said conductors being mechanically distinct, and one of said conductors being non-metallic and having high specific resistance, to establish a high resistance junction; one of said conductors having an excessive structural high resistance, and means'fo'r obviating the deleterious effect of the excess of resistance.

7. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two -massive electrical conductors cooperatively having high thermo-electric power and in good contact with each other, said conductors being mechanically distinct, and one being non-metallie and having high specific resistance, to establish a high resistance junction; one of said conductors being a relatively soft substance of high structural resistance which is reducible by the application of pressure; and means for compressing said compound to reduce its resistance to an effective degree.-

8. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive elec trical conductors cooperatively havinghigh thermo-eleetric power and'in good contact with each other, said conductors being mechanically distinct, and one being non-metallic and having high specific resistance, to establish a high resistance junction; one of said conductors having a relatively soft and laminar structure of high' ohmic resistance which is reducible by the application of pressure; and means for compressing said'cond'uctor to reduce the laminae resistance and produce effective high resistance.

9. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high thermo-electric power and in good electrical contact with each other, said conductors being mechanically distinct, and one being non-- metallic and having high specific resistance, to establish a high resistance junction; one of said'conductors possessing an excessive structural resistance in series with the junction; and a clamp to compress said high resistance conductor and reduce its resistance.

10. Oscillation-detecting means forreceiving intelligence communicated by electric 'waves, which comprises two massive electrical conductors cooperatively having high thermo-electric power and in contact with each other, said conductors being mechanically distinct, and one being non-metallic and having high specific resistance, to establish a high resistance'junction; one of said conductors' possessing excessive structural resistanee in series with the junction; a clamp to compress said excessive resistance (10nductor to reduce its resistance; and a spring for pressing said conductors together to establish a good contact at the-high resistance junction.

.11. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive elec trical conductors cooperatively having high thermo-electric power and in good electrical contact with each other, said conductors being mechanically distinct, and one being non-metallic. and-having high specific resistance, to establish a high resistance junction; one of said 'conductor's'poss'essing an excessive structural resistance in series with the junction; and means for compressing said high resistance conductor to reduce its resistance to an operative degree.

12-. Oscillation-detecting means for receiving intelligence commumcated by electric waves. which comprises two massive electrical conductors cooperatively having high thermo-electric power and in contact with each othen said conductors being mechanically distinct. and one being non-metallic aml having high specific resistance, to establish a high resistance junction; one of said conductors being a mass of a soft chemical compound. and the other conductor being a pin of a relatively harder material; and means for pressing said members together to establish an electrically and mechanically stable contact at thehigh resistance junction.

13. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive elec-, trical conductors cooperativelyhaving high thermo-electric power and in good electrical contact with each other. but mechanically distinct. to establish a high resistance junction; one of said conductors being molybdenite, having excessive resistance between its laminae; and means for compressing the molybdenite to reduce its resistance to an operative degree.

14. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cotiperatively having high thermo-electric power and in contact with each other. but mechanically distinct, to establish a high resistance junction, one of said conductors being the chemical compound molybdenite, and the other being the metal bismuth; and means for compressing the molybdenite to reduce its resistance to an operative degree; said conductors being in ood contact with each other at their high resistance junction, and having low resist ance circuit contacts.

15. Oscillation-detecting means for receiving intelli ence communicated by electric waves, which comprises two massive electrical conductors coiiperatively having high thermo-eleetric power, and in contact with each other, but mechanically distinct, to establish a high resistance junction, one of saidoconductors being a chemical compound of a non-metal and a metal; and means for establishing a good electrical contactat the high resistance junction of said conductors, low resistance circuit contacts for said conductors.

trical conductors cooperatively having high thermoelectric power and in contact with each other, but mechanically distinct, to cs;

tablish a high resistance junction, one of said conductors being a chemical compound of a non-metallic substance and a metallic substance; and means for establishing good electrical contact at the highresistancc junction of said conductors. and low resistance circuit contacts for said conductors.

1T. Oscillation-detectingmeans for receiving intelligence connnuni-ated by electric waves; which comprises two ma sive electrical conductors cooperatively having high thermo-electric power and in contact with each other, but mechanically distinct, to establish a hi h resistance junction, one oi said conductors being a chemical compound of a metal with the non-metal sulfur: and means for establishing good electrical contact at the high resistance junction of said comluctors, and low resistance circuit contacts for said conductors.

1R. Oscillation-detecting means for receiving intelligence mmmunicatcd by electric waves, which comprises two massive electrical conductors cooperatively having high thermo-electric power and in good electrical contact with each other, but mechanically distinct, to establish a high resistance junction, one of said conductors being a relatively soft high non-metal with a metal; and means for establishing good electrical contact at the high resistance unction of said conductors, and low resistance circuit contacts for said conductors.

l9. Oscillation-.detecting means for receiving intelligence communicated by electric waves, which con'iprises two massive electrical conductors cooperatively having high thermo-electric power and in good electrical contact with each other, but mechanically distinct, to establish a high resistance junction, one of said conductors being a soft chemical compound of a non-metallic substance with a metallic substance; and means for establishing good electrical contact at the resistance chemical compound of a and low resistance circuit contacts for said conductors.

20. Oscillation-detecting means for receivirig intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high thermoelectric power and in good electrical contact with each other, but mechanically distinct, to establish a high resistance junction, one of said conductors being a high re sistance compound of a 'nonmetallic substance with a metallic substance and means for establishing good electrical contact at the high resistance unction of said conductors, and low resistance ci'i niti contacts for said conductors.

21. Oscillation-detectingj ineans for receiving intelligence communicated by electric waves, which comprises two massive electrical conductors cooperatively having high I thermo-electric power, and in electrical contact, but mechanically distinct, to establish a high resistance junction; said conductors having low resistance circuit contacts; said conductors having a material relative differ ence in the property of hardness; an insulat ing support having a perforation containing one of the conductors, said support resting against the other conductor; the conductor in the perforated support being longer than the support; and means for pressing through the perforation and against the other conductor, the conductor contained in the perforation, to cause the harder conductor to sink into the softer conductor.

22. Oscillation-detecting means for receiving intelligence communicated by electric waves, which comprises two massive elec trical conductors cooperatively having high thermoelectric power,'and in electrical contact, but mechanically distinct, to establish a high resistance junction; said conductors having low resistance circuit contacts; two supports bearing on opposite sides of one conductor, one of the supports being of insulating material perforated to receive the other conductor and permit it to engage the first conductor and means for clamping the first conductor between said supports.

23. A means for converting the energy of the feeble oscillating currents produced by intelligence transmitting electro magnetic waves, into a form-suitable for operating direct-current indicating instruments, which comprises two substantially non-attenuated and substantially non-comminuted conducting contact members, one of which consists of a chemical combination of a metallic element with a non-metallic element, said chemical combination possessing the ability, when operatively in substantially perfect electrical contact with the other contact member, to furnish a direct current from the energy of the applied oscillating current.

24. A means for converting the feeble osl cillating currents produced by intelligencetransmitting electro-magnetic waves, into a form suitable for operating direct-current indicating instruments, which comprises two substantially non-attenuated conducting contact members, one of which consists of a chemical combination of a chemical element with at least one" other chemical element, said chemical combination possessing the ability, when operatively in substantially 27. A rectifier for small oscillatory cur-' rents consisting of molybdenite.

28. A receiver for wireless telegraphy systems consisting of a compound of molybdenum and sulfur in contact with electrodes.

29. A rectifier for small oscillatory currents consisting of molybdenite in contact with electrodes.

30. A receiver for wireless telegraphy systems consisting of molybdenite in contact with electrodes.

31. A receiver for wireless telegraphy systemsconsisting of a' sheet-of molybdenite, and electrodes engaging opposite sides of the sheet.

32. A means for converting the energy of the feeble oscillating currents produced by intelligence transmitting electro magnetic waves, into a form suitable for operating direct-cyrrent indicating instruments, which comp ises two substantially non-attenuated and substantially non-comminuted conducting contact members, one of which possesses the ability, when operatively in substantially perfect electrical contact with the other contact member, to furnish a direct current from the energy of the applied oscillating current.

33. A means for converting the energy of the feeble oscillating currents produced by intelligence transmitting electro magnetic waves, into a form suitable for operating direct-current indicating instruments, which comprises two substantially non-attenuated and substantially non-comminuted conduct-' ing contact members, one of which consists of a chemical combination of a metal with at least one other chemical element, said chemical combination possessing the ability, when operatively in substantially perfect electrical contact with the other contact, member, to

furnish a direct current from the energy of the applied oscillating current.

GREENLEAF ,WHITTIER PICKARD. Witnesses? EDWARD H. ROWELL, MYnA STACKPOLE RowELL. 

